Biology STAAR (State of Texas Assessments of Academic Readiness) Practice Test

What function do villi serve in the small intestine?

1. They protect against pathogens

2. They help in the absorption of nutrients

3. They aid in the production of digestive enzymes

4. They neutralize stomach acid

The correct answer is: They help in the absorption of nutrients

Villi play a crucial role in the functioning of the small intestine by significantly enhancing the absorption of nutrients. The small intestine is where most digestion and nutrient absorption occurs, and the presence of villi increases the surface area available for these processes. Each villus is covered with even smaller hair-like structures called microvilli, which further amplify this surface area. This design allows for a greater number of nutrients, such as amino acids, simple sugars, vitamins, and minerals, to be absorbed into the bloodstream efficiently. The vast network of blood vessels inside each villus then transports these absorbed nutrients to various parts of the body to support growth, energy, and overall health. While protecting against pathogens and aiding in the production of digestive enzymes are important functions of the intestinal system, these roles are not the primary functions of villi. Similarly, neutralizing stomach acid involves other mechanisms, such as the secretion of bicarbonate by the pancreas, rather than the action of villi directly.